PASSENGERS at Sydney Airport and across Australia will increasingly be forced to endure long delays because the airport is pushing the brink of its capacity.

Analysis prepared for a government inquiry into a second airport site for Sydney shows that within a decade, relatively minor disruptions to morning flights will delay flights for up to five hours over the rest of the day.

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The analysis also shows Sydney Airport's limited ability to accommodate new flights means airlines are finding it harder to fly into the city when they would like.

The federal government, which has committed to nominating a site for another airport this year, is expected to seize on the figures to help justify the cost of a second airport.

One piece of analysis, by the consultants Booz & Company, shows the burden on passengers through the day if morning flights are disrupted.

By 2015, the analysis suggests, if flights at Sydney were limited to 55 an hour in the 7am-9am peak due to bad weather, it would take three hours, or until noon, for the airport's schedule to recover.

The delays would frustrate travellers at Sydney, but also those at other airports whose flights link with Sydney.

By 2020, the analysis suggests, the same morning delay would set back the flight timetable by five hours, or until 2pm.

"It's clear Sydney needs a second airport sooner rather than later," the Transport Minister, Anthony Albanese, told the Herald yesterday.

"Without action the national economy will be constrained with a negative impact on growth and jobs."

Mr Albanese has commissioned a joint federal-state study into locations for a second airport which is due to report by the middle of the year.

The study is expected to canvass as many as 10 locations. But Labor's former preferred site, Badgerys Creek, has already been ruled out.

Mr Albanese will argue that a second airport for Sydney is a national economic priority, not just an issue for the city.

A separate piece of research prepared for the federal Department of Infrastructure shows that airlines are increasingly unable to fly into the city at their chosen time.

Federal legislation limits the number of aircraft movements at the airport to 80 an hour.

But at the start of 2011, airlines requested more than 80 flights an hour on seven different hours. For the same period last year, the number of bids by airlines exceeded 80 on only four hours.

The chief executive of Airport Co-ordination Australia, which manages the hourly slots at Sydney Airport, Ernst Krolke, said there was increasing pressure on the 80 flights an hour cap.

But Mr Krolke said he was still able to accommodate new demands for flying into Sydney.

A spokesman for Qantas acknowledged the lack of spare capacity at Sydney. "Capacity constraints at Sydney Airport do create pressure on peak hour operations, which can have knock-on effects for the rest of our network," the spokesman said.

Sydney Airport, owned by the publicly listed MAp Group, says the constraints are artificial. "The 80 movements per hour cap is an arbitrary regulatory cap that does not reflect the capacity of the existing infrastructure at Sydney Airport," a spokesman said.

He said the airport would tell a Productivity Commission inquiry into airport regulation to review the constraints.

"This will also remove the need for the government to spend substantial taxpayer funds to construct additional aviation capacity elsewhere."

At a forum in Parramatta in February, Mr Albanese said it would be a tragedy if Australia missed out on economic opportunities because of a lack of space at Sydney Airport. "You already have the case that we could fill more capacity than is there with the growth in our region … the growing travelling public of China in particular, but also India and other countries," he said then.